This invention relates generally to document transport drive systems, and more particularly to a variable speed document transport drive system for use in an encoder station to increase the system throughput.
Prior art encoder stations, such as the encoder station employed in the Burroughs S100 proof encoder system, utilized a drive system wherein the check was moved to the encoder station at 75 inches per second (ips). As soon as the document enters the encoder station at 75 ips, it is stopped when it contacts a closed pressure roller assembly and it is registered. The closed pressure roller assembly then drives the document at the encoding speed of 21/2 ips for the encoding operation. When the end-of-encode signal is given, the pressure roller assembly is pulled open and the high speed drive rollers will exit the document at 75 ips. After the trailing edge of the check clears the edge sensor, the pressure roller assembly closes and is ready to stop the next incoming document. This system is relatively slow since the document is driven from its leading edge until the end of encoding at 21/2 ips and the continual engagement and disengagement of the pressure roller assembly can cause mechanical failure, document damage, and the generation of excessive noise.